Electron beam tube



Dec. 9, 1941. F. PREISACH E TAL ELECTRON BEAM TUBE 2 Sheets-Sheet 1Filed March 23, 19.59

Dec. 9, 1941. F. PREESACH ETAL.

ELECTRON BEAM TUBE Filed March 23, 1939 2 Sheets-Sheet 2 I Fig- PatentedDec. 9, 1941 ELECTRON BEAM TUBE Ferenc Preisach and Imre Zakarias,Budapest, Hungary, assignors to United Incandescent Lamp and ElectricalCompany, Ltd., Ujpest,

Hungary Application March 23, 1939, Serial No. 263,708 In Germany March29, 1938 3 Claims. 01. 250-151) Our invention relates to electron rayvalves,

more especially of the kind in which means are provided for deflectingthe electrons of the ray. It is an object of our invention to improvethis type of valves in several respects, as will appear more in detailas the specification proceeds.

As is well known, electrical alternating voltages can be amplified bydirecting the electrons of an electron ray in timely alternation fromone collector electrode onto another by influencing;-

ing facts can be ascertained. If one succeeds in? so far increasing thesensibility of the electron control (mutual conductance of the valve) bya suitable dimensioning of the deflecting control members, as is thecase in space-charge controlled valves, it will be found that theinner;-

resistance in the electron ray valve is considerably lower, so that anamplification such as is possible with a space-charge controlled screengrid valve, is not obtainable. On the other hand the electron ray valveswith deflection control; offer the basic advantage, as compared with thespace-charge controlled valves, that the electrons are not braked, theelectron paths being only deflected through small angles, whereby theformation of space-charge clouds in the, high frequency field isavoided, which are known to involve certain disadvantages at higherfrequencies. These disadvantageous effects are particularly known in themodern mixing valves (hexodes, octodes); the distribution control, by,vmeans of the outer control grid, which is employed in these valves, isnot a deflection control, because here the paths of the electrons arebent completely, whereby disadvantageous phenomena arise.

The improved electron ray valve according to the present inventioncombines the advantages offered by the deflection control with the highamplification value of the space-charge controlled screen grid valves.

In the drawings affixed to this specification and forming part thereof avalve embodying our invention is illustrated diagrammatically by way ofexample.

In the drawings:

Fig. 1 is a diagram of connections of this valve, while Figs. 2-5 showdetails of diiferent arrangements of the screens and anodes.

Figs. 6 and '7 are diagrams showing further modifications of the valveaccording to this invention.

In all the figures K is the cathode, G the control grid, A1 andAzacceleration and ray concentration electrodes, respectively, P1 and P2deflecting electrodes, SG, SG1 and SGz are screen grids, BG is thesuppressor grid, A and A are working anodes, HA is the auxiliary anode,S and S are electrodes for concentrating the ray to about cathodepotential. L1 is the inductivity and C1 the capacity of the inputoscillation Y circuit, L2 and C2 the inductivity and capacity,

respectively, at the output of the valve; C3,' C4 and C are bridgingcondensers, E is an' anode voltage source, R a voltage dividerresistance and St and St are electron paths. On testing the innerresistance of the working anode A of an electron ray valve such as shownin Fig. 1, the following effects can be ascertained, which render theanode current dependent from the anode voltage:

1. Passage from the anode A to the control member PzP1.

2. A secondary emission exchange between the working anode A and theauxiliary anode HA.

3. A deflection of the ray in the critical range at the passage of thebundle of rays StSt (passage of current) y from one anode to the other.

In order to avoid the first mentioned eifec t, it appears obvious toarrange a screen grid SG1 in front of the anodes A-I-IA, as is usual inspace charge controlled electron valves. In analogy with the screen gridvalves fitted with suppressor grids it is also advisable to avoid theexchange of secondary emissions by the insertion of a suppressor gridBG. The tests have however shown that by these obvious steps theintervalve resistance cannot be increased sufficiently. For it has beenfound that the differential inner resistance of the anode circuit in thecritical range of passage of current drops by one-tenth, for instancefrom 500,000 ohm to 50,000 ohm in in the case of an anode current of 3milliampere. Our invention is based on the perception that thiselectron-optical influence of the working anode on the intervalveresistance is decisive and that it can be done away with by thescreening methods according to this invention.

Arrangements of the screens and anodes embodying this invention areshown in Figs. 2-5. In all these arrangements the working anode A 'isseparated from the auxiliary anode HA by a screen grid SG, the workinganode A being always arranged behind the auxiliary anode HA, if viewedin the direction of the ray S t- St'.

If, int-an arrangement suchzaslshownin;-Eig i 2, th ray enters thecritical range,'if the mesh of the screen grid is sufficiently narrow, achange of the anode voltage become imperceptible at the point is.

In order to avoid an exchange of secondary emission with thescreenygri-dfSG;agsullpressor grid BG is further inserted ;etwe.en:thefscreen grid SG and the anode A Figi3.

A simplified and yet highly effective arrangement is shown in Fig. 4,where the sa'uxiliary' anode HA and the screen grid sG form a rna'jallxiliary ano'de, and a grid structure adapted 'to'take upsuhstantialcurrent provided between, and in a plane parallel to the planes of, thetwo ianodes forzthepurpose of substantially preventing 'anypassage fromthe working anode to said chanical and electrical unit, in which,the'surface of the auxiliary anode HA is continued bythe :surface ofthe screen gridss'Gi, -which maylhave the form of a wire-gauze or may beformed of windings. L'In i consequence of this arrangement the potentialis imainlyrdetermined, throughout the ientire i surface-and: thereforealso at 5 the criticeilepdintfkg-by: the voltage of th auxiliary anodeHA and depends from the anode voltage only in --proportion :to :thepassage :from the anode A -throughgtheisuppressongridzBG. 1

I elf-it :should prove cnecjessary, ta :further lscreen .grid L-ISGz canhewinsertedlbetween the auxiliary, --.:ano'de and;th;e suppressor:gri'dLBG :(E'ig. 5.).

1 .Inzzthe "combinations shown in :Eigs. 2,;3-and 5 v{the isoreen i gridSGi 1 can be connected with the auxiliaryanode insid,orloutsideofiitheivalve.

:the arrangements iaccording to :this ;in-

' mention the :amplificationefactor .of ttheiva'lve can :d iincrea-sedto more j than :20. eHowever, such values are; necessaryisin lordergtoattain -amp1i JCfifi-QII factors above 100 and valve resistances 'sahovel0.0,000 ohm,:vincthecase OfoflBOdG currents tahove :limilliampere,which u'ssagain necessary order to: obtainzmutualconductance valuesabove V ,i'IIhe electron .ray valve vthus requippedican be fitted withone or a plurality of control-members G ;inorder ;t o lbe;able to ;use:the svalve'raslamplifier or mixing valve or control waive.

;-I f it: is ;d esi red to;produce Jby .meansto'f an electron ray valvealternating anode .=curre nts of -a magnitude similar to that of etheusual aspacescha f e controlled-"electron valves, ithe electron raybundle must bezproduced by meansczof an electrode surface K of 6-1 cm.In that case it i very-useful to iform .the bundle normally to ;-.;thelongitudinal axis of :a prismatic :or .cylindric ;?-h0de K and ,tossubdivide 1it intoetwo :or more v bundles;accordinggtonFJigs.:.6ancli'7. ,v c

-Qn im syffo 'instance operate by ;.such an arra ement -az= mixingevalve; connection b ;arrang inabehin th c'athnde-K a spaceechargecontrol 1 i t the .scr emng. system :according J30 i'this I in ventionis illustrated .in Figs. 1+7 .only with -referenceeto theicase Where;the concentration .and

v deflec tign of the celi fitron .raymr zbundle of eleci mmra isefiectthat the-same; a easements will :also bringi'forth lelectrostatically,it .is evident z ll fl fi iq sma neticlor mixed i0 {and sdeflesticn. .Qfithe oelectmn r y deflecting means and any exchange of secondaryemission between the two anodes, whereby to ren'derithe electron paths.and-the inner resistance .of the working anode substantially independenti from changes of sthe :anojde tpotential ithrcughout theaangedf-ioperation.

22. An electron beam itubecomprising anJelectron remittingcathode,imeans .zfor deflecting .-.the .ele'ctrons,.-and electrodes-disposed.normally to the directionof the electron beam as emitted from -saidcathode,including an auxiliary anode, a working :anotie,y.said anodesbeing arranged in ---c ns.ec11tive :parailel planes, the plane of said:workingan'ode. being'disposed to J the rearv of said auxiliary 2 anode,:and :a a (grid structure adapted to take. up substantial: currentprovided :between. the ;two anodes :forthepurposeoft'tsubstantiallytpreventing any passage from the working anode to saiddeflecting means lalld any exchange (of. secondary zemission rbetweenthe two (anodes, said rid structure .comprising'lal screen .gridattached l.to,;andsdis posed in;the plane of, said auxiliary ,anQde .soas Lto "be. located sin'front of said worksing anode; whereby torender:the electron paths and theinner resistance 01 the working anode substantiallyindependent from changes of the anode potential throughoutthe range of opera i n.

-" An electron'heam tllbEiOOlIlDliSillg an. elecvtron ienittingicathode, means for "deflecting the electrons andelectrodes;dispcsed normally' to, the ldirectioniof the electron-beam.asemitted from said cathode-including an :auxiliary anode, .a

working anode,rsaid-anodes'ibeing arranged in consecutive :parallel"planes,v ;the plane of said Work n anodeibeins disposed to lthe rear ofsaid to tal:e' :upzsubstantial;;current provided between the twolainodes rorrthe purpose of substantially .ai xiliary anode, land ;a .z-rid structure adapted p even ing any m a e from -.:the workin anode tosaid deflecting means, and :any exchange .of

G :and then .providinganother deflection Lcontrol v as indicated ;forinstance .in Fig.7 -7 'iby rthe rods secondary emission betweemtheitwo;:an0de.s, said .'.g-. id.- structure zcomprising i a;screen grid:attached to, and diDQS8d in;the plane .of, saidiauxiliary anode so astobe located-infrontofsaidworking e, a '.-se nd s reen :grid and 'a'suppression grid arranged in consecutive parallelplanesbevtween, .andin parallel to the planes of, vsaid anodes, z-whereby to rendertheelectron pathsand the inner resistance o fthe working -anode;subs a t alyind pen e t r m: chanses;of:;the anode potential throughout the. rangeof operation.

7 V H'HF'ERENC-PREISACH.

' VIMRE ZA'KARIAS.

